[Object] To provide a protector that is detachable with one hand and that eliminates the need of re-gripping a medical needle to perform puncture； and a medical needle assembly constituted by a combination of the protector and a medical needle.[Solution] A protector 1 is a protector that is detachably fitted and attached to a medical needle 2. When a proximal end portion of the protector 1 is pressed in a state in which the protector 1 is attached to the medical needle 2, the fitted state thereof is thereby released, and the protector 1 is detached from the medical needle 2.
